EVIDENCE: Police search pond banks for clues and Det Ch Supt Steve Worron holds up a photo of a jacket similar to that of the killer [EASTNEWS PRESS AGENCY]

Officers drained a nearby pond this morning and got on their hands and knees in a search for vital evidence.

The murderer of 31-year-old student Nahid Al-Manea fled the scene in Colchester, Essex, on Tuesday morning after stabbing her 16 times.

He was spotted on CCTV coming out of an alleyway near the secluded Salary Brook Trail where the savage attack occurred.

Her body, which was wearing a long Islamic gown and headscarf, was found at 10.40am in the outskirts of the city near a region of fields.

It has not been confirmed whether the woman's death was racially-motivated.

The suspect is described as aged between 18 and 25, of medium build with thick dark hair.

His mac-style jacket is light brown with lapels and a matching belt.

Det Chief Superintendant Steve Warren, who is leading the investigation, urged local residents to check their gardens and bins for any suspicious items that look like they have been discarded by the killer.

ON CAMERA: CCTV image of Nahid Al-Manea walking in the street on the morning of the fatal attack [ESSEX POLICE]

“In my experience of people who kill in this way, they do not stop until they are caught”

Criminologist Prof David Wilson

The Saudi Arabian victim lived with her brother and was taking an English language course at the University of Essex as well as a PhD in life sciences.

Her brutal death comes after another Colchester resident was found in the city stabbed to death in March.

James Attfield died from 102 stab wounds near Lower Castle Park, just under two-and-a-half miles away from where Al-Manea's body was found.

Criminology experts believe the murders were done by the same killer.

Prof David Wilson said both victims were “overkilled” in the attacks, which means they were stabbed more times than needed to kill them.

He said: “In my experience of people who kill in this way, they do not stop until they are caught.”

Residents of Colchester have been advised to not walk alone in unsafe areas, especially at night.

He added that the suspect is likely to be a local man who is known to mental health authorities in the area.

“Everything points to the fact the man lives locally.

“He has to have somewhere to return to having completed the murder.

“He would need to wash his clothes or discard the clothes,” he added.

Anyone with information is asked to contact the Major Investigation Team on 01245 282103, Essex Police on 101 or contact Crimestoppers, anonymously, on 0800 555 111.